Conventionally, when a mother board (main-board) and a plurality of sub-boards are to be connected, some considerations are made to prevent connection errors between the mother board and the plurality of sub-boards. For example, in a case where these sub-boards respectively use connectors having different numbers of pins, or these sub-boards uses connectors having the same number of pins, their positions on a mother board are set apart from each other. If, for example, there are a plurality of boards which control the same type of motor, connectors having different numbers of pins are intentionally prepared, or connectors having the same number of pins but having different shapes are prepared to prevent connection errors in assembly.
For example, Japanese Patent Application Laid-Open No. 9-237241 discloses a technique of receiving board information and physical information to form a table, registering corresponding logical numbers, and subsequently using the logical numbers for control.
According to Japanese Patent Application Laid-Open No. 9-237241, however, a control board is not allowed to be inserted in a connector at an arbitrary position on a mother board (DCON) without causing any inconvenience in control.
In addition, changing the shapes or numbers of pins of connectors leads to an increase in cost. Making the shapes of sub-boards, each having a similar function, different from each other also leads to an increase in cost. Furthermore, the connector layout on a board has recently become complicated as compared with before. Moreover, cables which connect a mother board and sub-boards differ in the number of wires for the respective connections. Consequently, as cable arrangements differ from each other in the overall arrangement, the types of cable arrangements to be used increase in number and diversify. For this reason, in apparatus assembly, an apparatus must be assembled without any errors by coping with such problems as well.
Japanese Utility Model Application Laid-Open No. 4-120129 discloses an arrangement in which slots (connectors) are provided on a mother board so as to directly connect a plurality of sub-boards. According to this arrangement, each slot recognizes the type of connected sub-slot. By virtue of this arrangement, any sub-board can be connected to any slot.
The arrangement by Japanese Utility Model Application Laid-Open No. 4-120129 is properly applicable to only a case where these sub-boards are directly connected to a mother board. However, in a case where a plurality of sub-boards are to be connected to several positions within an apparatus main body, these connection positions must be correct.
Provided that there are several sub-boards, each holding a motor, these sub-boards must be connected to respective proper installation positions so that each motor on each sub-board can drive proper part of an apparatus. In other words, even though a sub-board is connectable to any connector on a mother board via a cable, if the connection in an apparatus main body is incorrect, the apparatus can not operate properly.